Corrosion inhibited trichloracetates



2,829,039 CORROSION iNHmrrEn 'TRICHLORACETATES Harry Crawford James, James S. Sconce, and Joseph E. Thornberg, Niagara Falls, N. Ya, assignors to Hooker Electrochemical Company; Niagara Falls, N. Y., a corporation of New York p No Drawing; Application March I, 1954 1 Serial No. 413,459

8 claims. C1. 11-25 This invention relates to new compositions of trichloroacetates which have improved non-corrosive properties when in: contact with-the surface of metals. and to methods of minimizing the corrosive action of trichloroacetates on metallic surfaces. In particular, this invention relates to new compositions of the water-soluble salts of trichloroacetic acid and water-soluble benzoates, which compositions have improved non-corrosive properties wlienin contact with the surface of metals and which do not create an undesirable precipitation of'solids from the solutions containing these compositions.

Salts of trichloroacetic acidwhich aresoluble in water have found wide ranges of uses in the arts as weed killers, as agents for breaking petroleum water-in-oil type emulsions, such as are commonly found or obtained from pro-.

ducing oil wells or from the bottoms of oil storage tanks, and as catalysts for intermediates in certain chemical reactions. In the practical employment of trichloroacetates in theirapplications, the trichloroacetate of necessity comes into contact with metallic surfaces both before and after use, causing corrosion and rapid deterioration of such surfacesthereby making the use of these compounds to metals by adding to them a corrosion inhibitor which materially decreases the corrosive effects ofthe trichloroacetate; It is another object to provide such corrosion' inhibitors which do not adversely aflect the color of the resultant composition. A third object is to provide such compositions which do not cause additional precipitation of sludges beyond that encountered in the absence of the inhibition. A fourth object is to make available compositions of the water-soluble salts of trichloroacetic acid containing corrosion inhibitors which minimize the attack on metals due to pitting and etching and which minimize loss of weight of the metal.

We have found that these and related objectives are a complished by the present invention which comprises minimizing the corrosion of metals by the water soluble salts of trichloroacetic acid, by dispersing therein watersoluble benzoates whereby an improved trichloroajcetate composition is produced which when in contact with metals, causes only a fraction of thecorrosion which results when using the trichloroacetate alone, and does not impart objectionable color or sludge to the trichloroacetate, all as more fully described hereinafter.

. Among the compounds which we have found to be most effective for the purpose of this invention are the water-soluble benzoates, especially thealkali metal benzoates including the ammonium, lithium, sodium and potassium benzoates. Other water-soluble benzoates,

United States Patent 2,829,039 Patented Apr. 1, 1958 2 such as zinc, magnesium, aluminum,- and manganese benzoate, may also be effective in accomplishing the objectives of the invention.

Among the metals which we have found to be protected against corrosion by compositions of this invention are the ferrous metals, such as mild steel, Aluminum, copper, brass, galvanized metals and tin-plated metals also may be protected.

Satisfactory results are obtained in accordance with this invention by incorporating intothe trichloroacetate to be corrosion inhibited more than 011 and up to 4.0 percent on the dry weight basis of the corrosion inhibitor. More than 4.0 percent maybe used but little additional inhibition is observed even after extended exposure. Optimum results are realized in the corrosion inhibition of aqueous solutions of an alkali metal or ammonium trichloroacetate such as sodium trichloroacetate by incortions of this invention, the benzoates can be incorporated into the trichloroacetates by mere mechanical mixing. It is preferred to add the water-soluble benzoate in the dry powder form to the sodium trichloroacetate which is also in the dry form. a

The following examples are given to illustrate preferred embodiments of our invention and they are not to be construed as limiting except as defined in the appended claims. In all runs, except where indicated, technical grade sodium trichloroacetate (designated herein as STCA) commonly available in commercial quantities was used and was made up to a 45 percent by weight concentration with distilled water. All runs were conducted at room temperature of approximately twentyfour degrees Centigrade. Some of the runs were made using stagnant unaerated solutions while others were aerated. In those which were aerated, the air was bubbled in at a uniform rate; this provided agitation as well Chimneys were placed over the bubbling tubes to prevent air from impinging on the specimens.

Solids precipitated out on the bottom in all runs and were measured as volume percent after centrifuging 15 minutes at about 650 R. P. M. in a centrifuge whose rotational diameterwas 18 inches.

The solution pH was adjusted to between 7.5 and 10.5 with alkali as measured with a Beckman model G pH meter.

The specimens were placed in the solutions in two different ways: some were placed on the bottom of each container where they could be covered by the precipitate with the solutions being unaerated; and others were hung in the solutions above the bottom but totally submerged and the solution was air blown; The method of preparing the specimens was the same'in eachcase: metal pieces 3.0 inches by 1.0 inch by 0.05 inch were cleaned with number emery cloth and sapolio soap. They were then cleaned with alcohol, dried in the oven, weighed, andplaced in the solutions to be treated. Up: on removal from the corroding solutions, the specimens were washed with soap and water. if this did not remove the scale, they were made cathodic in an electrolytic cell using a current density of 20 amperes per square decimeter in an electrolyte of an inhibited solution of five percent by volume sulfuric acid. If this failed, they were scraped gently with a piece of magnesium and returned to the cell. This process was repeated until the specimens were cleaned. They were then washed with alcohol, dried in the oven and Weighed. The corrosion rate is reported as milligrams per square decimeter per day (mg/sq. dm./day). Percentages of inhibitors used are given on a solid STCA basis.

Example I.1S'tagnant solutions with steel specimens lying on the bottom Sodium Corrosion Benzoate Rate Run No. ConeenpH (mg/sq. Remarks tration, dmJday) percent 7. 3-8. 2 198 2.2% Solids. 7. 3-8. 2 196 Do. 8.1-8.5 67. 5 0.1% Solids. 8. 1-8. 5 14. 4 o. 8. 3-8. 5 4. 3 0.2% Solids. 8. 3-8. 5 4. 8 Do. 8. 1-8. 4 114 0.4% Solids. 8.1-8. 4 33. 7 Do.

Example 2.Aerated solutions with steel specimens suspended in liquid Sodium Corrosion Benzoate Rate Run N o. CoucenpH (mg/sq. Remarks tration, dm./day) percent 8. 4-8. 7 60 Solids. 8. 4-8. 7 41. 7 Do. 8. 4-8. 7 25. 2 Do. 8. -9. 3 24.1 0.17 Solids. o. 5 8.5-9.3 31.6 b0. 0. 5 8. 5-9. 3 18. 2 D0. 1. 0 8.5-9.1 8.0 1.0% Solids. 1. 0 8.5-9.1 7.0 Do. 1. 0 8. 5-9. 1 7. 5 D0. 2. 0 8. 4-8. 9 9. 6 0.47 Solids. 2. 0 8. 4-8. 9 7. 5 o. 2.0 8. 4-8. 9 8. 6 Do.

The water-soluble inorganic alkalies which may be employed in order to adjust the pH of the solution are the common alkalies such as sodium hydroxide, sodium carbonate, potassium hydroxide, etc., whereby new compositions comprising: Water-soluble salt of trichloroacetic acid, a water-soluble inorganic benzoate, as a corrosion inhibitor therefor, and, a water-soluble inorganic alkali, may be produced in accordance with this invention.

Among the water-soluble salts of trichloroacetic acid which are embraced within the scope of this invention are the alkali metal salts such as sodium trichloroacetate, potassium trichloroacetate, and including ammonium trichloroacetate, alkyl radical containing salts of trichloroacetic acid, etc.; it is to be understood that although sodium trichloroacetate Was employed in the above examples for the purpose of illustrating certain detailed embodiments of this invention, we do not contemplate being limited thereto except as defined in the appended claims.

A solid composition inhibited against corrosion to metals comprising a water-soluble salt of trichloroacetate and about a one percent by weight of a water-soluble benzoate to act as a corrosion inhibitor therefor was prepared on a commercial plant scale by neutralizing a solution of trichloroacetic acid with sodium hydroxide, drying the resultant sodium trichloroacetate in a vacuum dryer and adding to the resultant dry product about one percent of sodium benzoate as a corrosion inhibitor. This solid composition comprising sodium trichloroacetate and the benzoate inhibitor has been used successfully with the realization of improved resistance to corrosion when in contact with metals.

We claim:

1. A composition of matter comprising a water-soluble salt of trichloroacetic acid and as a corrosion inhibitor therefor, a water-soluble salt of benzoic acid selected from the group consisting of sodium benzoate, ammonium benzoate, potassium benzoate, lithium benzoate, zinc benzoate, magnesium benzoate, aluminum benzoate, manganese benzoate and mixtures thereof, present in about 0.1 percent to about 4.0 percent by weight of the water-soluble salt of trichloroacetic acid.

2. A composition of claim 1 wherein the water-soluble trichloroacetate is selected from the group consisting of sodium trichloroacetate, potassium trichloroacetate and ammonium trichloroacetate.

3. A composition of claim 1 wherein the corrosion inhibitor is sodium benzoate.

4. A composition comprising a water-soluble salt of trichloroacetic acid, a water-soluble salt of benzoic acid selected from the group consisting of sodium benzoate, ammonium benzoate, potassium benzoate, lithium benzoate, zinc benzoate, magnesium benzoate, aluminum benzoate, manganese benzoate and mixtures thereof as a corrosion inhibitor therefor, present in about 0.1 percent to about 4.0 percent by weight of the water-soluble salt of trichloroacetic acid and a water-soluble inorganic alkaline alkali metal compound present in amount sutlicient to adjust the solution to a pH between 7.5 and 10.5.

5. A solid composition being inhibited against corrosion of metals comprising a water-soluble salt of trichloroacetic acid and a water-soluble salt of benzoic acid selected from the group consisting of sodium benzoate, ammonium benzoate, potassium benzoate, lithium benzoate, zinc benzoate, magnesium benzoate, aluminum benzoate, manganese benzoate and mixtures thereof, present in about 1.0 percent by weight of the water-soluble salt of trichloroacetic acid to act as a corrosion inhibitor therefor.

6. The solid composition of claim 5 wherein the watersoluble salt of benzoic acid is sodium benzoate.

7. A method of retarding corrosion of metals by watersoluble salts of trichloroacetic acid which comprises incorporating in the trichloroacetate a water-soluble salt of benzoic acid selected from the group consisting of sodium benzoate, ammonium benzoate, potassium benzoate, lithium benzoate, Zinc benzoate, magnesium benzoate, aluminum benzoate, manganese benzoate and mixtures thereof in amounts between about 0.1 percent to about 4.0 percent by Weight of the water-soluble salt of trichloroacetic acid to act as a corrosion inhibitor therefor.

8. A method as in claim 7 wherein the metal is a ferrous metal.

Chemical Astracts, vol. 46 (1952), col. 6577c, abstract of article by Mercer. 

1. A COMPOSITION OF MATTER COMPRISING A WATER-SOLUBLE SALT OF TRICHLOROACETIC ACID AND AS A CORROSION INHIBITOR THEREFOR, A WATER-SOLUBLE SALT OF BENZOIC ACID SELECTED FROM THE GROUP CONSISTING OF SODIUM BENZOATE, AMMONIUM BENZOATE, POTASSIUM BENZOATE, LITHIUM BENZOATE, ZINC BENZOATE, MAGNESIUM BENZOATE, ALUMINUM BENZOATE, MANGANESE BENZOATE AND MIXTURES THEREOF, PRESENT IN ABOUT 0.1 PERCENT TO ABOUR 4.0 PERCENT BY WEIGHT OF THE WATER-SOLUBLE SALT OF TRICHLOROACETIC ACID. 